1. Technical Field
The disclosure concerns a neutral beam source in which the ion beam is directed to the neutralization grid at an angle determined by the configuration of the neutralization grid.
2. Background Discussion
Treatment modification of surface material of a workpiece such as a semiconductor wafer using an ion beam is well-known. Such treatment may include localized film property modification by a directional beam to enable selectivity improvement. Surface properties may be altered to enhance or inhibit nucleation, deposition and etching of the material. Use of an ion beam for such purposes involves certain limitations. For example, there is no independent control of beam angle and beam energy for an ion beam. Further, the ion beam spreads as it propagates toward the workpiece due to space charge. More importantly, the ion beam charges the surface of the workpiece, which can lead to damage of features formed on the workpiece. One solution to such problems is to employ a neutral beam instead of an ion beam. One need is to provide for optimization of the angle at which the ion beam strikes side walls of the neutralization grid for maximum neutral flux for a given incoming ion flux.